Process for improving the uniformity of the modulus of elasticity in a draw twist wound thread cop



Now 1 1. 1969 u. HERWIG 3,477,221

H. PROCESS FOR IMPROVING THE UNIFORMITY OF THE MODULUS 0F ELASTICITY IN A DRAW TWIST WOUND THREAD COP Filed Feb. 21, 1968 FIG. I

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HANS ULRICH HERWIG ATT'YS H. U. HERWIG Nov. 11. 1969 PROCESS FOR IMPROVING THE UNIFORMITY OF THE] MODULUS OF ELASTIFITY IN A DRAW TWIST WOUND THREAD COP 3 Sheets-Sheet Filed Feb. 21, 1968 FIG. 50

" INVENTOR HANS ULRICH HERWIG FIGS! EQ nEEE u q United States Patent 3,477,221 PROCESS FOR IMPROVING THE UNIFORMITY OF THE MODULUS OF ELASTICITY IN A DRAW TWIST WOUND THREAD COP Hans Ulrich Herwig, Erlenbach, Germany, assignor to Glanzstotf AG, Wuppertal, Germany Filed Feb. 21, 1968, Ser. No. 707,216 Claims priority, application Germany, Feb. 24, 1967,

G 49,389 Int. Cl. D02g 3/02; D01h 13/00; B65h ]/00 US. Cl. 57157 16 Claims ABSTRACT OF THE DISCLOSURE A process of draw twist winding a thread into a biconical cop according to a predetermined thread winding tension program as between the middle cylindrical portion of the cop and its reversal points, whereby a maximum difference in tension is attained after winding approximately the first one-third of the cop with the tension at the reversal points being less than about twothirds of the tension of the middle portion, followed by gradual convergence of the two tensions during the remaining winding operation until they are about equal upon completion of the finished cop. The resulting biconical cop exhibits an improved uniformity in the. modulus of elasticity of the thread in subsequent processing steps.

This invention relates to a process for the improvement in the uniformity of the modulus of elasticity of a draw twist thread as produced by a draw twist winding of a thread onto a spindle with a reciprocating traversing stroke axially of the spindle during the winding operation to form a biconical cop having a substantially cylindrical middle portion and conically tapered end portions. The modulus of elasticity is that measured during the course of thread Withdrawal from the wound cop, i.e. that thread property measured in accordance with German Industrial Standard (DIN) 52,829 and sometimes referred to as the force of extension."

The draw twist winding of a thread into a biconical cop is a well known operation in which the object isto draw out the thread while imparting a twist thereto as it is being wound onto a rotating spindle to form a thread or yarn cop. Conventional draw twist apparatus includes a set of rollers or similar means to stretch or draw out the thread and feed it to the rotating spindle around which there is placed a ring rail having a reciprocating traversing movement axially of the spindle, the

thread passing through a traveler which moves freely around the ring rail and then on the spindle to form the cop with a twist being imparted to the thread. By gradually changing the traversing stroke of the ring rail, the corresponding traversing movement of the thread as it is applied to form the cop results in a typical biconical construction of the cop with an essentially cylindrical middle portion and tapered end portions which correspond approximately to the reversal zones or the winding layers in the vicinity of the reversal points of the traversing stroke. The term draw delivery speed refers to the rate at which the thread is supplied to the spindle from the draw rollers and may be made independent of the draw ratio, i.e. the extent to which the thread is being drawn 3,477,221 Patented Nov. 11, 1969 from its original length. The term thread winding tension as employed herein refers to the amount of tension placed on the thread as it is being wound onto the rotating spindle.

It is generally known that the tension in the winding of the thread evokes certain changes or alterations of the thread immediately after it is drawn during subsequent storage on the yarn cop or yarn package. These change-s can be observed in drawing off the thread from the yarn cop, for example by measurement of the modulus of elasticity of the running thread. When the thread is employed as the weft material in a textile fabric or web, it has been found that such changes or fluctuations during the supply of the thread from a conventional draw twist winding lead to streakiness or striations in the fabric which are extremely undesirable and quite difficult to eliminate.

Various attempts have been made to prevent such striations or at least to alleviate the problem to some extent. However, even when accepting other substantial disadvantages such as a complicated winding geometry, unfavorable run-off thread tension, low speeds of production or the like, results have been only incompletely successful.

It is therefore an object of the present invention to provide a process of draw twist winding a thread into a biconical cop or bobbin in such a manner as to overcome the subsequent appearance of striations or similar noticeable imperfections in a fabric produced from these draw twist threads or yarn. More particularly, it is an object of the invention to produce a draw twist yarn cop according to a predetermined thread winding tension program which will result in a much more uniform modulus of elasticity as measured on the thread as it is subsequently withdrawn from the cop.

In accordance with the invention, it has now been found that fluctuations in the modulus of elasticity of the processed thread are the essential cause of streakiness or striations in the finished fabric product. This streakiness has also been found to be dependent on the cycle or period of the traversing stroke of the ring rail during the draw twist winding of the yarn cop. Furthermore, the modulus of elasticity is in turn determined predominantly by the position of particular portions of the thread in the winding and the course of the thread winding tension during the draw twist winding operation.

Normally the modulus of elasticity in the middle cylindrical portion of the winding is considerably smaller than in the region or zone of the two reversal points. In general, therefore, the process of the invention involves the influencing of the thread winding tension in a particular manner whereby one can avoid extreme fluctuations in the modulus of elasticity of the subsequently processed thread associated with the periodic traversing movement of the ring rail. More particularly, the thread tension during the draw twist winding is programmed in a specific manner so as to achieve the result that the moduli of elasticity of the middle portion of the cop and the two reversal zones are virtually equal or at least sufliciently uniform to avoid subsequent fabric imperfections.

Thus, in accordance with the invention, in the winding of the thread on a conventional draw twist machine, the thread winding tension is modulated in such a way, both over the course of each traversing stroke and also during the entire winding process, that the wide deviation in the modulus of elasticity of the subsequently withdrawn :and

processed thread as between the middle portion of the cop an its two end portions is substantially reduced and caused to be largely uniform during all subsequent processing.

This modulation or programming of the thread winding tension during the draw twist winding of the thread into a biconical cop essentially requires two sequential 'steps which may be defined as follows:

(a) Beginning with an approximately equal thread winding tension over the traversing stroke at the initiation of said winding, gradually diverging the amounts of said tension placed on said thread during succeeding traversing strokes as between the tension at and in the vicinity of the terminal reversal points of each traversing stroke and the tension in the middle portion of the same traversing stroke, with the tension at and in the vicinity of said reversal points becoming proportionately smaller than that in said middle portion, until reaching a maximum divergence of said tensions upon winding the first /2 to A, preferably about the first /3, of the total winding to be supplied to the finished cop, at which point the tension at said reversal points must be less than about /3, e.g., about to 7 and preferably about to of the tension in said middle portion; and

(b) Then gradually converging the amounts of said tension placed on said thread during the remaining traversing strokes as between the tension at and in the vicinity of said reversal points and the tension in said middle portion, until said tensions are again approximate- 1y equal upon completion of the entire winding of the finished cop.

Within these essential limitations of the thread winding tension program, the process of the invention can be carried out in a number of different ways which permit a simultaneous control of the quantitative amount of thread tension either in the middle portion of the cop or at the reversal points or in both regions in order to achieve the most advantageous tension values required for a particular thread or for a rapid cop construction according to known principles.

A decisive factor for influencing the course of the thread winding tension in the manner required by the invention is the magnitude of the ratio n/v in which n is the spindle turning speed or rotational velocity of the spindle in minuesand v is the draw delivery speed in meters/ minute. Thus, for the variation of the thread winding tension according to the program demanded by the invention, it is particularly desirable to alter this quotient n/ v as between the Zones of the reversal points and the middle portion of the cop. This can be accomplished by the appropriate alteration of one or both of the variables n and v.

Although conventional draw twist apparatus can be used to carry out the process of the invention, a variation in the ratio n/v requires the draw means to be driven separately and independently of the spindle. Likewise, the draw ratio of the thread should be governed separately from the output rate or draw delivery speed of the draw means. In this manner, one can achieve a constant draw ratio while varying either the draw speed and/or the spindle turning speed in relation to the position of the ring rail and also in relation to the progressive accumulation of wound thread, so as to regulate the amount of thread winding tension at any particular point of a traversing stroke of the ring rail as well as over the entire winding operation.

As the simplest technique for the variation of the spindle turning speed in the manner described herein, it has proven successful to provide means for switching off or stepping down the spindle drive during each traversing stroke as the ring rail approaches the upper or lower reversal points and then re-engaging the spindle drive or stepping up its acceleration when the ring rail reaches the reversal points. This measure can be supported so as to achieve accurate tension control, for example by means of a preferably controlled braking of the spindle during deacceleration and a controlled acceleration after re-engaging or switching on of the drive at the reversal points.

The best solution is achieved, however, by means of a positive control of the spindle turning speed or the draw delivery speed or both, depending upon both the position of the ring rail and the completeness of the winding operation, or in the latter case, preferably upon the winding diameter which is a measure of the extent to which the spindle has been wound. This positive control of one or both of the two speeds which regulate the thread winding tension can be accomplished by conventional means, for example by making use of variable speed drive motors or by the interposition of speed regulating gears between the drive means and the winding spindle and/or the draw means. Such means for controlling the rotational velocity of the spindle and/or the draw delivery speed are generally well known and can be readily adapted by a skilled mechanic for the specific purpose of programming the thread winding tension as required by the present invention.

According to one specific embodiment of the invention, the draw twist winding process is carried out such that the draw delivery speed is maintained at a constant value over the entire winding operation. The spindle turning speed, which is initially equal over the entire traversing stroke at the beginning of the winding operation is first gradually reduced during succeeding traversing strokes in the zone of the reversal points in relation to the turning speed in the middle portion of the cop preferably such that the spindle turning speed during each such stroke is lowered as the thread travels axially of the spindle from the middle portion of the cop to a reversal point and is then raised again as the thread travels axially of the spindle from the reversal point back to the middle portion. Viewed in sequence, each succeeding traversing stroke is accompanied by an increasingly lower spindle turning speed at and in the direction of the reversal points in comparison to the spindle turning speed in the middle portion of the cop. This procedure is followed until completion of approximately the first A of the total winding, e.g. about the first to /2 of the total net weight of the finished cop, at which point the turning speed at the reversal points should be about 65 to 82%, preferably 70 to 78% of the value of the turning speed in the middle portion of the cop. Then, the spindle turning speed in the zone of the reversal points is gradually increased in relation to that in the middle portion during the remaining traversing strokes until the two speeds are again approximately equal over the entire traversing stroke upon completion of the winding operation. During this convergence of the spindle turning speeds over approximately the last /a of the winding operation, one still observes a reduction in the turning rate in the direction of the reversal points and an increase in this rate when returning to the middle portion during each individual traversing stroke. In this case, however, the difference in the turning rate between the reversal points and the middle portion is being gradually reduced from one stroke to the next.

The spindle turning rate can be reduced linearly in the vicinity of and at the reversal points over the first stage of the winding operation and can then be increased linearly from its minimum value with a sharp bend or turn in the curve defining the rate of change. However, this variation of the turning rate may also be defined by a steady or continuous curve having a minimum value which lies in the zone of about the first one-third of the net weight of the finished cop. It is also possible, on the other hand, to vary both turning rates simultaneously, i.e. by increasing the turning rate in the middle portion while decreasing it in the zone of the reversal points, such that one runs through a minimum value for the reversal points and a maximum value for the middle portion at about the same time.

The spindle turning speed in the middle portion of the cop, which is of course equal to the turning speed at the reversal points only at the very beginning of the winding operation, causes the thread to be drawn onto the cop at gradually higher linear speeds as the diameter of the cop increases with reference to a constant rotational velocity of the spindle. The spindle turning speed can be maintained constant at the middle portion of each traversing stroke over the entire winding operation or it can be varied in a manner known in itself according to a specific thread winding program. Thus, it is possible to proceed in such a manner that the thread winding tension at the reversal points remains constant as well as in such a manner that this tension retains a constant value in the middle portion of the cop. It is also possible to vary both tensions correspondingly. In all cases, by adopting the particular thread winding tension program according to the invention, the problem of improving the modulus of elasticity can be solved.

The desired alteration of the thread winding tension can also be accomplished according to the invention by varying the draw delivery speed with a constant draw ratio, while maintaining the spindle turning speed at a constant value or at values programmed in a known manner over the entire winding operation but remaining substantially constant in each traversing stroke. It is, of course, also possible to simultaneously control both the spindle turning speed and the draw delivery speed so that their combined alternation produces the desired thread winding tension during each traversing stroke and over the entire winding operation.

Thus, according to another embodiment of the invention, while observing a constant spindle turning speed and a constant draw ratio over the entire draw twist winding operation, the draw delivery speed which is initially equal over the entire traversing stroke at the beginning of the winding operation is first gradually increased during succeeding traversing strokes in the zone of the reversal points in relation to the draw delivery speed in the middle portion of the cop. Thus, during the first stage of the winding, each succeeding traversing stroke is accompanied by an increasingly higher draw delivery speed at and in the direction of the reversal points in comparison to the draw delivery speed in the middle portion of the cop. This relative increase of the draw delivery speed at and in the vicinity of the reversal points is continued until completion of about the first /3 of the total winding, e.g. about the first A to /2 of the total net weight of the finished cop, at which point the draw delivery speed at the reversal points should be about 120 to 150%, preferably 125 to 140%, of the draw delivery speed in the middle portion of the cop. Then, the draw delivery speed in the zone of the reversal points is gradually decreased in relation to that in the middle portion during the remaining traversing strokes until the two speeds are again approximately equal over the entire traversing stroke' upon completion of the winding operation. During both the relative increase and decrease of the draw delivery speed at the reversal points throughout the winding operation, each traversing stroke preferably follows a pattern in which the draw delivery speed is raised as the thread travels axially of the spindle from the middle portion to a reversal point and is then lowered as the thread travels axially of the spindle from each reversal point to the middle portion.

The process of the invention, by appropriate control of the ratio n/v, makes it possible to achieve the desired divergence and convergence of the thread winding tension as between the middle and reversal regions of the cop while at the same time imposing a particular amount of thread tension on either the middle or the end portions of the cop. Thus, in some instances, it is preferable to maintain an approximately constant tension on the middle portion of the cop over the entire winding operation while controlling the tension in the reversal zones in such a way that at the point of maximum divergence, i.e. after winding about of the cop, the tension at the reversal points is reduced to a value of about ,5 to 1 3, preferably about /5 to /2, of the constant thread winding tension in the middle portion.

Alternatively, the thread winding tension at the reversal points can be maintained approximately constant over the entire winding operation while the tension in the middle portion of the cop is controlled in such a way that upon reaching approximately of the total winding, again corresponding to the point of maximum divergence, the tension is increased in the middle portion to about 1.5 to 10, preferably 2 to 5, times the constant thread winding tension at the reversal points.

In some cases, it may be desirable to maintain the thread winding tension constant at either the reversal points or the middle portion over only one stage or a portion of the entire winding operation while varying the difference in tension as prescribed herein, or it also is feasible to vary the thread winding tension both in the middle portion of the cop and also at the reversal points over the entire draw twist winding operation. In any event, the maximum difference in the thread winding tension as between the middle portion and the reversal points is reached upon winding the first A to /2 of the total winding, i.e. in the zone of the first /3 of the total net winding weight, and this maximum difference must be about A to preferably about /2 to V5 of the thread winding tension in the middle portion of the cop.

By following the procedure or tensioning program according to the invention, one obtains a draw twist wound biconical cop of highly improved uniformity of the modulus of elasticity as measured on the running thread as it is withdrawn or unwound from the cop. This biconical cop is essentially defined in terms of the thread tensioning program by which it was wound according to the invention, i.e. in which approximately the first onethird of the windings exhibit a gradual divergence in thread tension as between the middle cylindrical portion of the cop and the two reversal zones, with a maximum divergence or difference at this point where the tension at the reversal points is to preferably /5 to /2 of the tension in the middle portion, and in which the remaining two-thirds or so of the windings exhibit a gradual convergence of the thread tension as between the middle portion and the two reversal Zones with an approximately equal tension in the final winding layer. Slight variations are naturally permissible, provided that one does not stray too far from the thread winding tension program defined herein. Thus, a few layers may be wound in an identical manner so that the divergence or convergence of the tension values proceeds in incremental stages, but in general it is preferable to follow a completely continuous program in order to avoid any possibility of sudden fluctuations in the thread tensions from one winding layer to the next.

The fact that the thread winding tension can be in-fiuenced by a variation of the spindle turning speed is not new in itself. Thus, for example, British Patent No.

1,023,103 recommends the control of the spindle turning speed or of the thread tension as measured on the thread between the draw delivery or feed point and the so-called balloon thread guide which is normally positioned directly above the 00p, in the conventional draw twist machine. This control is carried out according to an empirically determined program in which the balloon thread tension can be continuously increased or decreased over part or all of the entire winding operation, the exact technique depending upon the type of thread being used and the desired structure of the yarn package.

The measures taught in this British patent are merely directed to achieving the highest possible winding speed during the entire operaiton by adaptation of the spindle turning speed to the highest possible speed of the traveler on the ring rail, thereby improving the efficiency of the draw twist machine as much as possible in comparison to normal operation with a constant rotary speed of the spindle. Although the thread winding tension can vary over the entire winding operation described in this patent, no provision is made to regulate the thread tension in response to or dependent upon the individual traversing strokes or cyclical movement of the ring rail. Accordingly, yarn packages or cops produced by the method of this patent still show the objectionable streakiness or striations in the further processing of the thread into fabrics, particularly after dyeing the fabric. Thus, this patent fails to solve the problem which has been remedied by the present invention, as will become apparent from several of the examples set forth below.

The process of the invention is further explained by the following examples, including the graphical illustrations set forth in the accompanying drawings wherein:

FIG. 1 sets forth a winding diagram for a so-called HV-winding, i.e. a stroke displacement winding or deck winding, the shaded area representing the zone in which the quotient n/ v is reduced;

FIG. 2 sets forth a winding diagram for a so-called HM-winding, i.e. a stroke reduction winding or biconical parallel winding, the shaded area having the same meaning as in FIG. 1;

FIGS. 3a, 3b and 3c illustrate the course of the spindle turning speeds, the thread winding tensions and the moduli of elasticity, respectively, over the entire winding operation as carried out in Example 1 below;

FIG. 4 sets forth the course of the differences of the moduli of elasticity over the entire winding operation, in one case the difference between the E-modulus in the middle of the cop and the upper reversal zone and in the other case the corresponding difference between the E- modulus in the middle of the cop and the lower reversal zone, both as taken in conjunction with Example 1 below;

FIGS. 5a, 5b and 5c are similar to the curves illustrated in FIGS. 3a, 3b and but are taken in conjunction with Example 4 below;

FIG. 6 is similar to FIG. 4 but is taken in conjunction with Examples 5 and 6 below.

In order to facilitate a comparison of results, all of the working examples except Example 1 have been summarized in the table set forth below. Furthermore, in the first four examples, a procedure was followed such that the programming of the spindle turning speed in accordance with the invention occurred only in the zone of the lower reversal point with reference to the middle portion of the cop so that the zone of the upper reversal point provides a basis of comparison. This provides a striking demonstration of the specific programming of the thread winding tension according to the winding operation of the invention.

The last two examples should be considered together. Example 5 discloses the results of a winding operation programmed both with reference to the traversing stroke of the ring rail and also over the entire course of the winding, while Example 6 gives a standard of comparison by employing a constant turning speed throughout the winding operation. The fact that a comparison between the results of Examples 5 and 6 is possible is clearly shown by Examples 1 to 4; however, the behavoir of the modulus of elasticity and its tendency to fluctuate widely does not change when merely controlling the spindle turning speed over the whole winding operation.

It will of course be recognized that a combination of the simple control of the spindle turning rate over the entire Winding process as previously known with the variation of the quotient n/v in dependency upon the traversing strokes of the ring rail movement as required herein generally leads to the best results. This combination thus provides not only the known advantages from the control or variation of the turning rate over the whole operation, i.e. the variation of the rotary speed of the spindle with increasing weight or diameter of the cop,

but it also provides the advantage of a more uniform modulus of elasticity according to the measures of the present invention.

In each of the following examples, the following values were maintained constant in each case:

The modulus of elasticity was measured after storage of the wound spool or cop for 14 days in a so-called standard climate. The values for the modulus of elasticity were obtained from the measurement of the force of extension with Dynagraph according to DIN 53,829 with 5% elongation at 50 meters/min:

Force (grams) 2 Titer (denier) Elongation where E represents the modulus of elasticity, sometimes referred to as E-modulus.

In the table and elsewhere below, the index or subscript 0 identifies the cylindrical middle portion of the cop (at the half stroke level, i.e. in the middle of the traversing stroke), while the subscripts 1 and 2 represents the lower and upper reversal points, respectively. As noted above, 11 represents the spindle turning speed in metersand E is the modulus of elasticity in grams (force)/ denier. F is the thread winding tension in grams (force). AE represents the difference in modulus of elasticity, likewise in grams(force)/denier, as between the middle or half stroke level of the cop and the lower and upper reversal points, respectively, as given by the following equations:

E grams denier In the first four examples, these two magnitudes are not the same because only the lower reversal point was controlled in accordance with the invention. In the last two examples, the values of A E and A E are equal because both reversal zones were controlled whereas Example 6 ran without control of the reversal zones.

In the last column of the table, the elfects achieved by the measures of the invention are entered in percent, in one case for control over the ring rail traversing stroke alone and in the other case for control both over the ring rail stroke and also over the entire course of the winding. For the control over the traversing stroke alone, a comparison can be made in Examples 2, 3 and 4 where the control was exercised only in the lower reversal zone:

In the last two examples, there is no basis for comparison as regards control over the traversing stroke alone since the lower and upper reversal zones were both controlled.

The effect of a control or programming both over the traversing stroke and also over the entire winding is entered in the table for Examples 3 and 5. This percentage can be obtained by a comparison between Examples 2 and 3 in one case and Examples 5 and 6 in the other case, according to the equations:

Example 3:

Effect (percent) X 100 A (II) -A E (III) Example 5:

Elfect (percent) X 100- The Roman numerals in parentheses are the run numbers as given in the first column of the table and correspond to the example number.

Referring now to the drawings, FIG. 1 represents a conventional winding diagram of a so-called HV-winding in which the lines or curves 1 and 2 represent the positions of the reversal points in the traversing stroke (H) for the net winding weight (G) of the cop plotted on the abscissa 3. The shaded areas enclosed by line 1 and line 4 at the top and line 2 and line 5 at the bottom indicate approximately the zone in which the thread winding tension is varied in accordance with the invention by variation or control of the quotient n/v over the traversing stroke of the ring rail. In other words, the vertical distance between the broken lines 4 and 5 corresponds approximately to the uncontrolled middle portion of the cop while the shaded areas represent the controlled reversal zones with reference to each traversing stroke. The maximum divergence of thread winding tension occurs at about of the completed winding weight as indicated by vertical line 6.

The same type of diagram is illustrated fora so-called HM-winding in FIG. 2. The lines or curves 7 and 8 represent the positions of the reversal points while the broken lines 9 and 10 taken with lines 7 and 8, respectively, enclose the shaded areas representing the reversal zones where the quotient n/v is varied in accordance with the invention.

The description of FIGS. 3-6 is given in conjunction with the appropriate working examples below.

Example 1 This example is considered as Run No. I and is not contained in the table.

A Perlon yarn (polycaprolactam) of denier 60/12 was wound with an HV-winding as in FIG. 1, in which process the turning speed of the spindle in the middle portion of the cop and also at the upper reversal point was the same and was maintained constant over the entire winding operation, while in the vicinity of the lower reversal point this turning speed was gradually lowered over the winding process up to about /3 of the net weight of the cop, and thereafter gradually and continuously raised again. The course of the turning speeds, as well as that of the winding tension and the modulus of elasticity are illustrated by the curves plotted from concrete values in FIG. 3. FIG.

3a shows the course of the turning speed, in which 11 represents the turning speed for the middle portion and the upper reversal point, while the broken line or curve 12, 13 represents the course of the turning speed at the lower reversal point. The minimum of the turning speed at the lower reversal point lies at about A of the net weight of the cop (line 14 With this control of the turning speed wherein n is varied in each traversing stroke only in the lower reversal zone, there results a difierent thread winding tension for the cop middle portion 15, the upper reversal point 16 and the lower reversal point 17, as shown by the correspondingly numbered curves for the course of the tension as represented inFIG. 3b.

FIG. 3c shows the course of the modulus of elasticity in which line 18 is that of the middle portion of, the cop and lines 19 and 20 represent the E-modulus for the lower and upper reversal points, respectively.

In the diagram of FIG. 4 the E-modulus variations or differences between the middle of the cop and the upper and lower reversal points are plotted over the net weight of the cop. In particular, the line or curve 21 shows the diiference between the modulus of elasticity at the upper tial by the programming of the turning speed at the lower reversal point is clearly evident.

Example 2 A Perlon yarn as used in Example 1 was wound with the HM-winding as shown in FIG. 2. The other conditions corresponded to those of Example 1 with respect to a control or programming of the spindle turning speed only in the lower reversal zone.

The results are recorded in the table under Run No. II.

Example 3 A thread of the same material as used in Examples 1 and 2 was wound into an HM-winding. The spindle turning speed was controlled in the cylindrical middle portion and at the upper reversal point in such a way that the thread winding tension remained about constant, while at and in the vicinity of the lower reversal point the turning speed was reduced with respect to the turning speed in the middle portion of the cop corresponding to the vertical distance between the broken lines 9 and 10 in FIG. 2.

As can be seen from the table, where the data are tabulated, the course of the E-modulus at the lower programmed reversal point showed a marked improvement in comparison to that at the upper reversal point. Thus, the E-modulus at the lower reversal point coincides much more closely with the E-modulus in the middle portion of the cop so that on essentially avoids any noticeable variation or fluctuation of the E-modulus during subsequent traversing withdrawal of the thread. Moreover, this example makes it quite evident (see table) that an appreciable improvement in the course of the E-modulus could not be achieved when working according to British Patent No. 1,023,103.

Example 4 The same Perlon yarn (nylon 6) as in Examples 1 to 4 was wound into an HM-winding corresponding to the diagram of FIG. 2. The spindle turning speed was controlled at the lower reversal point in such a way that the thread winding tension remained constant at this point.

FIG. 5 illustrates in graphical form the various values with which the invention is concerned.

increases until reaching about the first third of the total cop weight and it then gradually decreases.

FIG. 5c gives the course of the modulus of elasticity with reference to the cop weight, i.e. over the entire winding. It can be seen from the course of line 29 for the upper reversal point as compared to the lines for the cop middle portion 27 and the lower reversal points 28 just how well the modulus of elasticity at the lower reversal point approaches that in the middle portion of the cop. The same successful results can also be easily derived from the table below.

Example 5 The thread material used in this run was Perlon, 40/ 10 denier. The type of winding employed was the so-called stroke reduction winding (HM) as illustrated in FIG. 2.

The thread winding tension was maintained approximately constant at a value of 0.6 grams at the upper and at the lower reversal point (F and F respectively); only the initial values are somewhat different (see table). To achieve this constant tension, it was necessary to reduce the spindle turning rate at the reversal points over the total running time from 6400 min." to 3450 min- 11 During each stroke, however, immediately after passing through a reversal point of the ring rail movement, the spindle turning speed was increased as the thread being wound moved toward the middle of the cop, so that at the center or half stroke height, the values achieved in The invention is hereby claimed as follows:

1. A process for improving the uniformity of the modulus of elasticity of a draw twist thread as measured during the course of its withdrawal from a wound cop, wherein said cop is produced by draw twist winding of said thread the cylindrical middle portion of the cop for the winding onto a spindle with a reciprocating traversing stroke axialtension or force (F over the running time go through 1y of the spindle during the winding operation to form a maximum. In particular, after about of the total a biconical cop having a substantially cylindrical middle running time, the values of F are considerably greater portion and comically-tapered end portions, said process than the values at the reversal points. The reversal zones comprising: and middle portion of the cop were essentially influenced draw twist winding said thread to form said biconical the same as explained in connection with FIG. 2. cop according to a predetermined thread winding ten- The results recorded in the table show that the third sion program of set of values used in this example led to an overcompensa- (a) beginning with an approximately equal thread tion of the E-modulus differential (A E and A E). As comwinding tension over the traversing stroke at the pared to the E-modulus value in the middle portion of the initiation of said wlndin g ly diverging cop, there occurred a slight deviation downwardly. This in the amounts of said tension placed on said itself clearly shows that by following the teaching of the thread during succeedmg traversing strokes as present invention, the problem of achieving a uniform E- between the tension at and in the viclnity of the modulus can be solved with any desired precision. With termlnal reversal polnts of each traversing stroke only a few preliminary trials, it is possible to closely conand the tension in the middle portion of the form the values of E-modulus throughout the entire Same tfavefslng Stroke, Wlth the tenslon at and winding. in the vicinity of said reversal points becoming Example 6 proportionately smaller than that in said middle In order to have a standard of comparison for the fi m reachmg I maxlmum dlllergenlce results achieved according to Example 5, another experiof sald tenslqns P W1nd1ng th first /2 i ment was carried out with the same thread material, which of the tta1 W1nd1I 1g to be PP to finlshed was wound with a constant spindle turning rate through- P, at Whlch P0111t the tenslon at 531d rel/6115211 out. The results are recorded in the table. pomts must be less than about /3 of the tension For a demonstration of what can be achieved even with in said middle portion; and simple means in following the teaching according to the (b) then gradually converging the amounts of invention, the E-modulus differentials are contrasted in said tension placed on said thread during the 6 for f yp of P g during remaining traversing strokes as between the tencourse of the wlndlng process. Under conditions otherwise sion at and in the vicinity f Said reversal points the a the Wmdmg w s condlicted normzjllly one and the tension in said middle portion, until said Ease, 1.e. attlt1 a constantflslpin 1e turmng rate asfliln Examplei tensions are again approximately equal upon m ano er case. W1 programming Over 6 ml completion of the entire winding of the finished stroke and finally 1n the last case w1th programmlng both Go over the ring rail stroke and also over the entire winding 40 2 A m Z' as claimed clam 1 wherein at Said dnt operation. The results (AE) are represented by the curve f c d t l t 32 for a constant turning rate, the curve 30 for program- 0 maxlmum e t f Wm enslgm a ming over the ring rail stroke alone, and the curve 31 for the reversal pomts 9 5 traviirsulg StrPke about 4? to the last case. /3 of the thread wlndlng tension in sald middle portion. In the following table there are tabulated the results A Process as f Clalm 1 Whfirelfl at 531d of Examples 2 through 6, in each case with an HM-windpolnt of maxlmum divergence, the thread w1nd1ng tension ing. at the reversal points of said traversing stroke is about Efiect percent by control over Spindle turning E-modulus Cop speed Winding tension E-modulus difierential Entire net (minr (grams) (grams/denier) (grams/denier) winding Run Example weight Stroke and No. No. Yarn Titer (grams) n; no n1 F2 F0 F1 E2 E0 E1 213 A113 alone Stroke 0 6,400 6,400 6,400 3.5 3.6 3.7 33.6 33.6 33.6 0.0 0.0 240 6,400 6,400 5, 500 8.6 2.; 8 .8 Z 610 6,400 6,400 5,000 .2 .0 H l i i c iih (T1m 6/12 870 6, 400 6,400 5,400 6.2 6.3 3.9 31.0 23.8 29.3 7.2 5.5 1,230 6,400 6,400 5,800 6.3 6.4 5.0 23.9 19.5 23.9 4.4 4.4 1,620 6,400 6,400 6,400 6.3 6.4 6.4 30.3 30.3 30.3 0.0 0.0 0 6,400 6,400 6,400 3.5 3.6 3.7 33.0 33.0 33.0 0.0 0.0 300 5,800 5,800 4, 700 3.2 3.2 1.2 29.0 23.2 26.2 5.8 3.0 m 3 do 610 5,400 5,400 ,100 3.4 3.4 1.1 28.6 21.9 24.6 6.7 2.7 850 4, 900 4, 900 4,050 3.0 3.0 1.4 28.3 21.6 24.3 6.7 2.7 1,210 4,750 4, 750 4,300 3.1 3.1 2.2 25.6 21.6 24.9 4.0 3.3 1,610 4,700 4, 700 4, 700 3.1 3.1 3.1 25.0 25.0 25.0 0.0 0.0 0 5, 500 5, 500 5,500 1.1 1.1 1.1 28.6 28.6 28.6 0.0 0.0 280 6,000 6,000 4,900 3.1 3.2 1.0 30.3 32.8 25.8 6.5 2.0 W 4 do 560 6, 000 6,000 4,500 3.5 3.6 1.0 27.4 21.3 23.8 5.6 2.0 800 5,600 5, 600 4, 500 2.9 2.9 1.0 25.5 20.4 22.5 5.1 2.1 1,300 4,100 4,110 3,700 1.5 1.5 1.0 25.2 21.5 24.0 3.7 2.5 1, 610 4,000 4,000 4,000 1.2 1.2 1.2 23.8 23.8 23.8 0.0 0.0 0 6,400 6, 400 6, 400 0.8 0.8 0.9 29.4 29.4 29.4 0.0 0.0 230 5,200 6, 400 5, 200 0.6 2.3 0.6 23.8 23.8 23.8 0.0 0.0 :3 53 33 523 -2 32 33 3% 3% r v .2 0 0 0. V g 900 4,250 5,700 4: 250 0.6 2.0 0.6 23.0 22.5 23.0 0.5 0.5 1,080 4,080 5,300 ,080 0.6 1.7 0.6 23.1 23.1 23.1 0.0 0.0 1,520 3,300 4,500 3,800 0.6 1.1 0.6 23.0 21.3 23.0 1.7 1.7 1,810 3,450 3,700 3,450 0.6 0.7 0.6 21.9 21.9 21.9 0.0 0.0 0 6, 400 6, 400 6, 400 0.8 0.8 0.8 27.7 =27 27.7 =0 =0 200 6,400 6,400 6,400 27.2 22.9 27.2 4.3 4.3 400 6,400 6, 400 6, 400 27.9 21.7 27.9 6.2 6.2 VI 6 do 840 6,400 6,400 6,400 (Not measured) 28.6 21.1 28.6 7.5 7.5 620 6, 400 6, 400 0,400 28.5 21.0 28.5 7.5 7.5 1,050 6,400 6,400 6,400 30.2 22.8 30.2 7.4 7.4 1,550 6, 400 6,400 6,400 30.9 26.0 30.9 4.9 4.9 1,790 6,400 6,400 6,400 31.6 =31 31.6 =0 =0 13 /s to /2 of the thread winding tension in said middle portion.

4. A process as claimed in claim 1 wherein said point of maximum divergence is reached upon completion of approximately the first /s of the total winding to be supplied to the finished cop.

5. A process as claimed in claim 1 wherein the alteration of said thread winding tensions as between the zones of said reversal points and the middle portion of said cop is carried out by variation of the quotient n/ v wherein n denotes the spindle turning speed and v denotes the draw delivery speed in feeding said thread onto said cop.

6. A process as claimed in claim 5 wherein said draw delivery speed is maintained at a constant value over the entire draw twist winding operation, and said spindle turning speed, which is initially equal over the entire traversing stroke at the beginning of the winding operation, is first gradually reduced during succeeding traversing strokes in the zones of the reversal points in relation to the turning speed in said middle portion until reaching a maximum reduction of the spindle turning speed at the reversal points upon winding the first to /z of the total winding, at which point the turning speed at said reversal points is about 65 to 82% of the turning speed of said middle portion, and then gradually increasing the spindle turning speed in the zone of the reversal points in relation to the turning speed of said middle portion during the remaining traversing strokes until said turning speeds are again approximately equal over the entire traversing stroke upon completion of the winding operation.

7. A process as claimed in claim 6 wherein the spindle turning speed during each succeeding traversing stroke is lowered as the thread travels axially of the spindle from the middle portion to a reversal point and is raised as the thread travels axially of the spindle from a reversal point to said middle portion.

8. A process as claimed in claim 5 wherein said spindle turning speed and the draw ratio of the thread is maintained at a constant value over the entire draw twist winding operation, and the draw delivery speed, which is initially equal over the entire traversing stroke at the beginning of the winding operation, is first gradually increased during succeeding traversing strokes in the zone of the reversal points in relation to the draw delivery speed in said middle portion until reaching a maximum increase of the draw delivery speed at the reversal points upon winding the first to /2 of the total winding, at which point the draw delivery speed at the reversal points is about 120 to 150% of the draw delivery speed in said middle portion, and then gradually decreasing the draw delivery speed in the zone of said reversal points in relation to the draw delivery speed in said middle portion during the remaining traversing strokes until these draw delivery speeds are again approximately equal over the entire traversing stroke upon completion of the winding operation.

9. A process as claimed in claim 8 wherein the draw delivery speed during each succeeding traversing stroke is raised as the thread travels axially of the spindle from the middle portion to a reversal point and is lowered as the thread travels axially of the spindle from a reversal point to said middle portion.

10. A process as claimed in claim 5 wherein the initial divergence of the thread winding tensions and their subsequent convergence as between said zones of the reversal points and said middle portion of the cop are accomplished by the combined alteration of the spindle turning speed and the draw delivery speed.

11. A process as claimed in claim 1 wherein the thread winding tension in said middle portion of the cop is maintained approximately constant over the entire winding operation, and the thread winding tension at and in the vicinity of said reversal points is controlled in such a way that upon reaching approximately /a of the total Winding, corresponding to the point of maximum divergence, said tension has been reduced at the reversal points to a value of about to /a of the constant thread winding tension in said middle portion.

"'12. A process as claimed in claim 11 wherein said thread winding tension at said reversal points is reduced at the point of maximum divergence to a value of about /5 to /2 of the constant thread winding tension in said middle portion.

13. A process as claimed in claim 1 wherein the thread winding tension at said reversal points is maintained approximately constant over the entire winding operation, and the thread winding tension in the middle portion of the cop is controlled in such a way that upon reaching approximately /3 of the total winding, corresponding to the point of maximum divergence, said tension is increased in said middle portion to a value of about 1.5 to 10 times the constant thread Winding tension at the reversal points.

14. A process as claimed in claim 13 wherein said thread winding tension in said middle portion is increased at the point of maximum divergence to a value of about 2 to 5 times the constant thread winding tension at the reversal points.

15. A process as claimed in claim 1 wherein the thread winding tension both in the middle portion of the cop and also at the reversal points is varied over the entire draw twist winding operation.

16. A process as claimed in claim 15 wherein the maximum difference in thread winding tension as between said middle portion and said reversal points is reached upon winding approximately to first /3 of the total winding and amounts to a value of about /2 to V5 of the thread winding tension in said middle portion.

References Cited UNITED STATES PATENTS 3,137,987 6/1964 Potts 5793 XR 3,259,337 7/1966 De Ruig 242-178 3,325,985 6/1967 Bucher 242-26.3 XR 3,357,655 12/1967 Iwnicki et a1. 5794 XR 3,358,433 12/1967 Curtis et a1. 5793 3,377,793 4/1968 Whittaker 5793 MERVIN STEIN, Primary Examiner W. H. SCHROEDER, Assistant Examiner US. 01. X.R. s7 94; 24226.1

ag UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3377 221 Dated Nmmmhm: J] 5 Inventor(s) [3 high, Hgflig It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 45, "minues" should read --m1nutes--.

Column 11, in the table, run no. IV, under "n "4,110" should read "4,100".

SIGRED mm SEALED FEB 2 41970 -U Amt:

M H- Fletcher, If

Officer WILLIAM E. 'SCIHUYLER, JR. Oomissioner of Patents 

